I'm in BEAM for about a year now, while I write
this diary. You've probably seen the Tilden bot spyder. I think that's the
ultimate bot, and I think most BEAM'ers think the same. To start such a bot, you
should think everything over very well. I had done some experiment's in the last
few months on different electronic problems, like a Pulse width modulated motor
controller, working with op-amps and microcores (had only used bicores before).
The second thing I broke my brain on, was the
motor orientation. I saw somebody construct a bot (named spyder too, sorry I
forgot your name/URL, will add link if discovered) that had a motor for lifting
and a motor for expanding the leg. This results (if legs are placed at 90
degrees from each other) in a zigzag walking motion.
I want to prevent that from happening, so if
the leg reaches forward, the leg should expand, and contract if moved
backwards.
If you have a look at Tilden's Spyder, you'll
discover that the "knee" is exactly as the human knee; the pivoting under leg
moves in the same plane as the perpendicular plane of the pivoting-mechanism.
this seemed like a good thing to copy-paste into my bot.
Because the under leg doesn't move right under
the pivoting-point, but is already pivoted to the outward a bit, the movement of
the under-leg is not purely forward or backward, but there is an increasing
upward/downward movement if the leg is extended.
Because I don't want to make calculations with
sinusoids in IR³,
lets get the first Taylor plynome of the pivoting circle between the two maximum
angles. Didn't get that? just take the two maximum angles of the under-leg and
draw a line between the points where the foot is in those positions then.
If the total angle is small, the line will be an acceptable model of the real
orbit of the foot. The angle will be about 60 degrees, so that's acceptable. If
the maximum angle in contracted position is assumed somewhere under the
pivot-point, the up/down movement and the forward/backward movement is roughly
the same
Tilden's spyder. My big role model (not Tilden, the bot!)